Governor



Nov. 8, 1927.

A. FQ MEYER 1648419 GOVERNOR Filed March 6, 1925 3 Sheets-Sheet l :gu-IIIIHIIIIII- f/V VEN TOR /c/GI] HozJ/DH MEYER /YrToR/YE fs Nov. s, 1927. 1,648,419

A. F. MEYER GOVERNOR Filed March 6, 1925 3 SheetSSheet 2 '1- g f I 33511 56 .//v VEN Ton /76Z j #50E/DH MEYER 7 TroRA/Ers Nov. 8, 1927. 1,648,419

A. F. MEYER GOVERNOR Filed March 6. 1925 3 Sheets-Sheet 3 [Nn/:wrok /loz PH f Marc-R C YDMIQMQT m TToR/vf y:

Patented Nov. 8, 1927.

" Amman F. nrnnaon entre. :i

GOVERNOR.

Application lecl 3ro-h invent-ion relates o `a new andA im- This proved regulator forth@ control of liuid flow and pressure. use as meantI for 'the automatic maintenance of any desired load on a driven member Working under a friction load produced by fluid-pression. This regulator capable of a. Wide `variety of uses in which a sensi?. fe and responsive automatic control. of fluit pressure and flow is desired. ln the selected embodiment. of the invention herein disclosed, this novel `regulator is shown as adapted for use in the Wood-pulp lraking. art.V is particularly adapted for use in connection vith the Well-known electric motor-driven frindstonee used for the production of Wood- Julp.

`This novel regulator entirely automatic in action. lt always increases the` fluid pressure and flow Vwith the least reduction in i friction load and decreases the pressure with the least increase in friction load.

An object of the invention, therefore, is to provide au improved device for controlling,- fluid pressure. v

A more specific object to produce a means for thc automatic maintenance of a deired load on a driven member Working under a. friction load produced byV fluid pressure. i

(Ether objects of the invention will more fully appearfroin the following` description and the a".:companyingl drawinejsand will be pointed out in theannexeoclaims.

ln the accoinpanyina drawings there has been disclosed a structure designed to carry out the objects of the invention. but .it irs-to beundcrstoocl that the invention is not to ,be confined to the exact features shoyvnae` various may be made ".vithin the scope of claunsntluch 'fell-ovv. v

En the drawings:

Figure l is a vertical i. i L through the valve s ructure with in the running position;` Y y l4`1eure 2 is a vertical sectional vieta/'on the line `EVM-Zot Figure l; and v sectional view the valve lt is particularly adapted for Serial No. 13,48.;

by a driven shaft. An instrumentality is provided to press Woodv placed in pockets against `the 'face of the grindstones7 and usuallyconsists of a piston having a head movable in a cylinder.. The opposite end of the pistonis provided With a foot by means ,l which the wood is pressed against the .ndstonc face. It is to be understood that,

re mounted upon a shaft, but each grindthese cylinder and pistondevices for press'- ingg' thewood in the several pockets against grindstone. The grindstone is thus operated under friction 'load induced by L' i offivood thus forcibly held against ,eripheral surface. f 's f stolnary in this art to drive these grinder," by means of-hydraulic turbines or electric motors. As here 4shown `the device is adapted to grinders driven Aby an electric motor. lt ishighly desirable. to keep the friction `load on the grindstones and theref fore the current consumption and voltage of the elect 1ic motor constant. Y f

.lt isalso common in this art to employ ay liquid under pressure not only .for the purpose of forcibly pressingthe Wood in the pockets against-the grinder by means of the piston, but `also toY usethis fluid pressure tov raise the piston l'iead away from the grindstone in order that the pockets-may be refilled. It should bel-,noted that the maintenance of the unifor'ln electrical load on these motors is effected by thenmintenanceof auniform L' J'on load on the v 1ir1clstones-` For eian'iole, when one pocket is pulled off for relillina it is obvious that nthe motorload' would be les .ed hence the pressure must beincreaeed upon the other pistons. A cornplication arises in that the amount of Huid, auch as Water. consumed in forcing the pistons in their normalworking movement to maintain objects engaged Wi th the grinder, is small; While the amount of water `consumed upon abnormal movement of each piston from; or to its object-maintaining positionvis relatively large.' These two factors malte' load control difficult. The invention includes an apparatus or mechanismnfhich controls the 'fluid flow and pressure supplied tothe pistons. lnthe selected embodiment here disclosed. there are preferably employed two oo-operable mechanisms. One of the mechanisms is actuated'by changes in the electricity flowing tothe electric motor, thatV is, in

its

one may be provided With-more than one of the amperage or voltage or both; and the other is actuated by changes in` the pressure and tlow ot' water to the cylinders andpistons. Only the latter mechanism is directly actuated by the abnormal movement of the piston. The former is indirectly actuated inasmuch as such abnormal movement causes instantaneous load changes. In order t-o prevent large load changes it is highly desirable that increased flow resulting from abnormal movement shall not cause a pressure drop in the cylinders which are pressing wood against the grindstone. In other words, variations in pressure resulting from variations in water flow .through the supply pase should be prevented so tar as possible. This novel structure eliects such result through the co-operation of the two mechanisms. y

The selected embodiment of this invention in combination with such motor-driven grinder is diagrammatically shown in Figure 8. Each grindstone 1 is fast upon the motor-driven shaft 2. A cylinder 3 is suitably mounted adjacent the peripheral surtace ot the grindstoneY and bears therein a piston-head 4 mounted upon the rod 5, the opposite end of which carries a toot 6 operating in the pocket 7to press objects, such as blocks of wood, against the surface of the grindstone whereby the wood is ground into pulp. Several such grindstones may be mounted fast upon the same shaft and, while several such cylinders and connections may be operatively associated with each grindstone, it is only necessary for the purpose of disclosure oi' this invention to show a single cylinder with each grindstone.

A passis provided which is adapted to supply a fluid, such as water, under pressure from a suitable source, to the wood-pressing cylinders. Herein such pass is shown as comprising a supply pipe 8 connected to a suitable source of supply of water under pressure and having the valve mechanism interposed in the supply pass between the pipe 8 and the ,pipe 9, which forms a continuation of the pass. This pipe 9 supplies the water under pressure in accordance with usual practice to each of the different pocket cylinders. As shown in Figure 3, passages 10 are shown as leading from the pipe- 9. Each passage is provided with a twoway valve 11, diagrammatically represented, which is manually operable either to divert the water under pressure to one side of the piston-head while permitting escape of any water on the other side of the head, or vice versa. In the position shown on the right in Figure 3, the right valve 11 is turned to permit water under pressure through the passage 10 and port 12 to the upper face of the piston-head 4 by which means that piston head is gradually downwardly forced to maintain the wood 'in engagement with the grindstone. This movement is termed, for salte of brevity, the normal movement. As the piston-head 4 is downwardly forced by means of pressure admited to the upper portion of the cylinder `through the port 12, any water in the lower portion ot' the cylinder may escape through the port 13 by way oi' the two-way valve 11 to the exhaust 14. The so-called abnormal movement of this wood-feeding instrumentality occurs when the valve 11 is manually turned halt way as shown in the left in Figure 3. In the position of this left valve 11, direct connection is had between the port 12 of the cylinder and the exhaust 14 to permit the escape of water from the upper portion of the cylinder and to direct the water under pressure Vfrom the passage 10 to the port 13 whereby thev piston-head 4 is upwardly forced to permit retilling of the pocket with wood. This abnormal movement, being substantially unopposed is relatively rapid and demands a relatively increased amount of water.

Similar abnormal movement, although of lesser magnitude occurs when the pocket has been refilled and the two-way valve 11 is then turned to the position shown on the right in Figure 3, so as to move the pistonhead 4 downward until the foot G again engages the blocks of wood.

This selected embodiment ot the novel governor is adapted automatically to maintain a uniform friction load produced by fluid pressure upon a member driven by an electric motor and includes mechanism operable by changes in fluid flow and pressure to reduce such pressure changes and a means electrically operable by the electricity supplied the prime mover to control the load.

The former mechanism includes a valve interposed in the iiuid pass leading from the source ot supply of fluid under pressure to the frictional load devices. This valve is partly controlled by a partition or diaphragm whose position is dependent upon the pressure in the pass; that is, when the pressure drops, the valve is more widely opened and vice versa.

The latter means consists generally in electrical means operable in response either to current consumption or voltage drop, or both, of the member-driving motor and is adapted also to control theposition of the same valve.

In the governor' here disclosed, the water under pressure is received from the pipe 8 through the port 1G and linds outlet through the section 17 of the pass. The valve structure includes a pressure chamber 18 provided by the casting 20. This casting is formed with a substantial annular waterway 19 communicating with the port 16 and inwardly opening into the pressure chamber. A double valve structure is provided to control the flow of water from the port'l16 and the water-way 19 intovithe passages 21 in the main casting which lead to the section 17. As this governor is usually erected in an upright position, as shown, the valve may be termed the upper, and the valve the lower. These two valves are fixed to the same stem 24 and terminally borne 'by the recessed boss 25 of the cap Z6 at one end` and by the spider bearing 27 of the supporting arches`28. The stem is thus mount# ed for reciprocatory movement in axialidirections. An upper valve seat 29 andv a lower valve seat 31 are provided by the cage 32 fitted within the annular portions 0i' the casting and the lower valve seat has a shoulder and recess mounting upon the lower portion of the casting.

The lower portion of. the pressure chamber has a continuation formed by the central recess 33 in the annular head 34 integrallyprovided by the opposed arches 28, The bottoni of this chamber continuation is closed-by a Ymovable partit-ionsuch as the diaphragm 35 of suitably flexible material such as a rubber composition.. TheV diaphragm 'is held in water-tight position by the ring 36 and they screws 37. The lower portion of the valve stem is reduced in diameter and provides a downwardly presented shoulder. duced stem portion extends through the diaphragm and receives a .washer 33 between the .diaphragm and shoulder and another washer 39 between the other tace ot the diaphragm and the terminal cap nut 41 received inthreaded engagement upon the stem. Then the nut lll is turned down7 the parts are so assembled that movement ot' the dia` phragm is communicated directly to the stem. i

the valve to seated 'position and to that end"1 the compression spring 42 encircles the boss 25 and tends to torce downwardly the upper the compresion spring 61 as will be hereafter described.

This water-pressure in the pressure chainber 53 is controlled by the electricity sup plied to the electric motor which drives the member or grindstone. his electric motor is preferably of the constant-speed type and its power consumption is dependent upon the friction load upon the grinders.

The two legs 13 rest upon the 'floor 44 and carry the relatively rthick ring 45 which has oppositely extending lugs 1G arranged in This re#` .spring (51 auch. obviously@th4 Means are provided which tend to torceV Such spaced pairs; The lower-lugs of .each pair are securely boltedto the legs 43`while the upper lugs of each pair are similarly secured to the. supporting arches 28. Preferably these legs are joined by a reinforcing bar. 47. The lower. opening of this ring Vis closed by a metallic plate i8 bolted to the under tace ot theA ring and having an interposed gasket to effect a 'watertight closure. The main diaphragm 49 similar to the auxiliary diaphragm 3,5 close; the upper opening oi' the ring and is held thereto by means ot the annulus 51 and the bolts The main pressure chamber 53 is tuus provided. A compression spring 5e is mounted to exert a force tending to push. the diaphragm downwardly.V

This spring is held between the diaphragm cap and an overhead plate tvadjustably mounted upon the three posts 57 upwardly extending through` the plate 56 and downwardly held by the adjusting nuts received in threaded engagement upon the upper ends ot these posts 57. f

The aboveanentioned compression spring' 61 is mounted between the. caps 62 and 63 and tends to thrust them apart. The upper spring cap 62 has an integral upwardly ex tending ball 6e which is seated within a socket-provided in the end oi the nut l.t1 while the lowerepring cap G3 has its under tace provided with a socket -for the reception l' L n v l or the ball 6o rorined upon the upper end ot the headed screw 66k whose shank:` extends through the diaphragm 49 and its cap 55.

lllliile a solid post may be used to communi.- cate the pressure in this main chamber to the valve stem 24, it is preferred to use this pring (31 is of relatively greater strength and stillness than the spring 42 and is graphicall so indicatedl in the drawings by means ot relatively greater size of wire.

The main chamber 53 is filled with water under pressure during vthe operation of. the governorand this chamber has communication with the annular water-way 19 or any other source ot relatively constant water pressure. The ring lfis termed with an integral neck G7 through which extends the port 68. The neck `67 is intermediately tapped and a pipe 69 is inserted therein for communication with the transverse port 63.'l

This pipo69 upwardly extends to a T l71v which has connection with the pipe 72 communicating with lthe waterway 19. A gatevalve or petcock 7 3 or an electricity-actuated pilot valve structure such as that shown on the left of Figure 1 as hereafter described, controls iiowVt-hrough the pipe 72. During the normal operation of the governor a small flow of watercontinues through the waterwvay 19, pipe 72, T 71, pipe 69, transverse port 68, to a gate-valve or petcocl; or tothe electricity-actuated pilot valve structure shown in Figure 1. Such a structure includes the valve chamber 7 4L formed in the casting bolted to the main valve structure. Flow from this valve chamber 74 to the discharge pipe 76 is controlled by the electricity-actuated pilot valves 77 and 78. Tf a manually controlled valve be used where the petcock 73 is shown, then an electricityactuated pilot valve must be used at the outlet or discharge port 63 as shown in Figure l. If an electricity-actuated pilot valve is used in place of the manually controlled petcocl 73, then either a manually controlled valve or an electricity-actuated valve may be used at the outlet port 68. The walls of the valve chamber 74 are preferably formed integrally with the casting 75 and provide an upper and lower valve seat for the upper and lower valves 77 and 78, the upper valve may have a slightly larger area. Tf so constructed this unbalance functions to cause these pilot valves fixed to the stem 79 to tend to unseat under pressure of the water. Such upward force eXerte-,d upon the valve stem 79 is communicated by the stem, through its pin engagement, to the short arm 8l of the lever pivoted upon the pin 82 carried by the bracket 83. The long arm 8st of this pivoted lever is engaged by a substantially knife-edge 35 adjustably carried upon the threaded link 8G pivotally connected to a plunger 87 slidably borne within electro-magnets 38 by means of the sleeves 89. These electro-magnets are preferably supported within a cooling oil-chamber bolted to the leg 91 which forms with the two legs e3, a three point support'r for the governor. The weight of the plunger 87 and the pull exerted by the electro-magnets, due either to the current flowing 'to the motor or to both the current and the voltage drop across `th-e motor-leads, tends to move'the valves from their seats. VVorling against such forces is the tension spring 92 adj ustably suspended by the threaded pin 93 and its wingenut 94: from the bracket S3.

During the running of this governor, water is led fronmthe water-way 19 through an electricity-actuated pilot valve or the pet- 'c ck 73 through the pipe 69 and the valve chamber 7d past the unseated pilot valves 77-78. The outflou7 from this valve chamber is controlled by the valves which are actuated through the medium of the electromagnets 38 energizable either by the current flowing to the electric motor which drives the grinder shaft or by the current and the voltage drop. The opening of the main valves 22 and 23 and therefore the fluid .flow and pressure are dependent, first, upon the pressure upon the diaphragm 35, and, second, upon the amount of water momentarily contained in the pressure chamber 53 of the governor` A current transformer 95 is connected into oneI or more phases of the current carrying wires 96 leading to the electric yvoltage drop across the motor leads.

example, the greater the loadon the motor,

motor 97 directly connected to the grinder shaft 2. By means of this transformer a small and relatively constant percentage of the electric current flowing to the motor is conveyed from. the secondary side of `the transformer to one of the electro-magnetic coils 88. There is also preferably employed a volta-ge trai'isformer 90 shunted across two of the leads to the motor and having its secondary side connected to the other of the two electro-magnetic coils 93 as merely diagrannnatically indicated in Figure 3. The plunger 87 thus exerts a pull on the lever arm S4 tending to open the pilot valve 77-78 in proportion to the current owing to the motor 97, or to the current andthe For the greater will be the current flowing, and, hence, the greater the pull exerted by a coil 83 to open the valves 7 7 7 8.

The pounds pressure exerted by the water, in the valve. chamber, against the unbalanced area of the pilot valve, if any, aided by the pull of the magnet, and the weight of the plunger 87 always just balances the pull exert-ed by the spring.

An increase in pull of the electro-magnet accompanying an increase in load on the motor 97, and therefore increased flow of elec# tric current to it, causes the pilot valve to open thus allowing the pressure in the chamber 53 to drop. Such a drop in this pressure which opposes the main spring 54 results in `a downward movement of the diaphragm 49, effecting a closing of the main valves 22-23 and therefore a reduction in fluid pressure,

friction load upon the grindstones and load upon the motor, andtherefore a reduction in pull of the magnet and a return to substantially normal load. When one of the pockets is pulled off for refilling or put on for movement of the foot 6, toward grinding position, such above mentioned abnormal movement causes an abnormal demand for fluid flow and hence there is first a drop in fluid pressure. Such a drop in fluid pressure in the main valve pass reduces the pressure on the diaphragm 35 which co-operates with the. main spring` 54. Therefore, the op posing water pressure immediately causes the main diaphragm a9 to move upward thus resulting in an opening of the main valves- 22 'and 23 to provide passage for the increased flow during the abnormal movement of the piston-head l? that was the cause of the drop in pressure.

lVhen the spring 61 is used in place of a solid post, it also serves to produce valvemovement simultaneously with pressure changes. Through such valve movement it tends to prevent pressure changes.

In the oase of motor driven grinders, a drop in pressure also causes an instantaneous reduction in load. This results in relll) duced pull by the electro-magnet and hence a closing of the pilot valves 77 and 78 followed by an increase in the pressure in the chamber 53 with the resulting further opening of the main valves 22 and 23 tobring the load back to normal.` It will thus appear thatthe main valve mechanism is actuated directly by fluid pressure and indirectly by change in electric motor load.

While not essential, itis preferred to employ a gauge 98 to indicate'grinding pressures and another` gauge 99` toy indicate .pressure in the main `chamber 5 3. Each such gauge is afforded operative communication with its chamber as shown.V l

Itwill thus be seen that if, for any reason, the pilot valves77 and 7 8 should become inoperativeand remain seated, the relatively large area of the diaphragm 49 would be subjected to the full vforce of the supply pressure with the result that the valve stem 24`might be upwardly thrust so far as to cause the upper valve 22 to strike the boss 25 andpartially disrupt the apparatus. The spring 61 is used as a cushion to counteract the effects of such a contingency. The prevention of such a contingency, however, is accomplished by means of a safety device shown in the upper left-hand corner of Figure 1, and the spring or safety device or both may be used, both being here shown. Y

This safety device includes a suitably supported cylindrical casting 101 having an integral inwardly presented annular valveseat 102 for the valve.103 whose stem 104 projects above and below the valve. The lower portion of the valvey stem is slidably Vborne for movement in aXialdirec-tions by the centrally apertured boss 105 of the flanged cap 106. The annular flange 107 of this cap provides a housing for the compression spring 108 whose lower end is supported by the inner face of the cap-nut 109 received in adjustable threaded engagement with the flange107. The upper end of the spring 108 carries the stem plate 111 by means of which the stem is upwardly vt-hrust to hold the valve in yieldably seated position. The upper end portion of the hollow casting 101 is counter bored to provide an upwardly presented shoulder to form an annular seat for the circular diaphragm 112 fixedly secured to the valve stem 104 whose unseating movement the diaphragm may effect. This upper portion of the casting is closed by the cap 113 which is screwedthereto and forms a pressure chamber above the diaphragm similar to lthe kone below the diaphragm. The pipe 114 provides fluid communication between this upper chamber and the fluid supply passentering the main valve housing 4 so that the grinding pressure isl` communicated'rather than the pressure von the sourceof-supply side of the mainfvalves 22 and 23.

The pipe 115 connects f with Vthe T 71 land thus provides fluid communication with the main pressure chamber 53 through the pipe 69 and port 68, the valve being partly bal` anced so far as such pressure is concerned. A discharge pipe 116 opens from the casting v 104 below the valve 103 to lpermitescape of fluid passing the valve 103.

The operation oftliis safety device or re lief valve may be explained upon the as@ ',siimption, for example, that the pilot valvesV 'U and 78 have failed to unseat during the pressure and hence` the pressure upon' thev upper side of the relief valve diaphragm 112 is increased above that for which the spring" 108 is adjustablyvset to resist. Therefore, the valve 103 is 4unseated` and fluid escapes past the valve and out the discharge lpipe 116 with the result that the pressure in the main pressure chamber 53 is reduced.

Having thus described myinvention what Iclaim as new and desire to se ure by Letters-Patent, is: i 1. An apparatus for the automatic maintenance'of a substantially uniform friction load produced by fluid pressure upon a member -driven by anelectric prime mover'in` cluding a passadapted tosupply fluid under pressure, a valve movable to' control the pressure under'whicli said fluid is supplied, elastic means straining to move the valve in one direction, an electrically operable device actuablein response to changes in said friction load, and fluid meansco-operable with said device straining proportionally to said friction load to move the-*valve in the opposite direction to provide a valve opening proportional to said friction load where-V by said friction load Vis automatically maintained.

2. An apparatusfor the automatic maintenance of a uniform friction load produced by fluid pressure upon 'a member drive-n by an electric prime mover including a vpass adapted to supply fluid under pressure, a v

valve movable lto control thepressure under which said fluid is supplied, elastic means straining to move the valve inone direction, an electrically operable device actuable in response to changes in said friction load, fluid means co-operable with said device straining to move the valve in the opposite direction to provide a yvalve opening proportional to said friction load whereby said friction load is automatically maintained,l and means for adjusting the elastic means wherebyits straining effort may be adju-stably altered;

V3. An apparatus -for theautomaticmaintenance of a substantiallyuniform frictionV load produced by fluid pressure upon a meinber driven byv an electric prime mover including` a pass adapted to supply fluid under pressure, a valve movable to control the pressure under which said fluid is supplied, elastic means straining to move the valve in one direction, fluid means straining` to move the valve in an opposite direction, and an electrically operated device actuable in response to 'changes in said friction load ifvary the straining effort of said fluid means Wherebyfthe uniform friction load is automatically maintained.

il. An apparatus for the automatic maintenance of a substantially uniform friction load produced by fluid pressure upon a ineinber driven by an electric prinie mover in cluding a pass adapted to supply fluid under pressure, a valve movable to control the pressure under which said fluit is supplied, elastic meansstraining` to move the valve in one direction, fluid means straining to move the valve in an opposite direction, and an electrically operated device actuable in response to changes in said friction load to vary the straining effort of said fluid. means, whereby the uniform friction load is automatically maintained, and complementary means actuable by fluid floiv through said. pass to control the pressure therein. t

5. An apparatus for the automatic maintenance of a substantially uniform friction load produced by fluid pressure upon means driven by an electric prime mover including,l a valve to control said fluid pressure, an electrically operable instrumentality, connections therefor to operate the same in accordance with the current consumed by the prime mover, means operable by said instrumentality to maintain a valve opening proportional to the current consumed by the prime mover, and complementary means actuable by the flow of said fluid to control the pressure thereof.

6. An apparatus for the automa-tic maintenance of a. substantially uniform friction load produced by fluid pressure upon means driven by an electric prime mover including` a valve to control said fluid pressure, an electrically operable instrumentality, connec-` tionstherefor to operate the same in accordance with the current consumed by the prime mover, means operable by said instrumentality to maintain a valve opening inversely proportional to the current consumed by the prime mover, and complementaryV means actuable bythe flow of said fluid to control the pressure thereof.

f 7. In an I apparatus for the automatic maintenance of a substantially uniform friction load produced by fluid pressure upon mea-ns driven by an electric vprime mover, y

including a valve operable to control the i amount of said fluid pressure, an electrical control device variablyrmovable m accordable by the lever to move the valve propor tionately to the movement of the devicev whereby the fluid pressure is `varied proportionately to said current consumption, and

complementary means -actuable by the flowv of said fluid .to control the pressure thereof.

8. ln an apparatus for the automatic` maintenance of a substantially uniform friction load produced-*by fluid pressure upon means dri-ven by an electric prime mover, including a valve operable to control vthe amount of said fluid pressure, an electromagnet and an Varmature therefor adapted to be moved thereby proportionately to the current consumed by the prime mover, a lever movable by the armature proportionately to said armatui-e-movement., means operable by the lever to move said valve proportionately to said" levermovement whereby the fluid pressure is variedproportionately to said current consumption, and complementary means actiiable by the floW of said fluid to control .the Apressure thereof.

9; In an apparatus for the automatic maintenanceof a substantially uniform friction load produced` by fluid pressure upon means driven by an electric prime mover,.in cluding a valve operable to control the amount of said fluid pressure,an electric device movable by and proportionately to the current consumed by the prime mover, means to impart movement to the valve proportionately to vthefmovement ofv the device whereby the fluid pressure is varied pro portionately to Vsaid current consumption, and complementary means actuable by the flow ofsaidv fluid to control the pressure thereof.

lO. n an apparatus for the automatic maintenance of a Ysubstantially uniform friction load produced by fluid pressure upon means drivenvbyan electric prime mover, includingn ya valve operablev to control the amount of said'pressiire, an electromagnet and armature therefor adaptedto be moved thereby.proportionately to the current consumed by the prime mover, means movable bythe armature to move said valve proportionately ktoarmature movement, and com.- plementary means actuable by the flow of said fluid to `control the pressure thereof.V

ll. In an .Zvpparatus for *the4 automatic maintenance of a substantially uniform friction load produced by fluid pressure upon means driven byan electricfprime Amover, including` la valve operable to control the amount ofv said pressure, an l'electromagnet and armature therefor' adapted to bemoved therebydirectly proportionately to the current consumed by the prime mover, means movable Aby. the armature to maintain ia valve opening inversely proportional to said current consumption, and complementary means actuable by the flow of said fluid to control the pressure thereof.

12. An apparatus for the automatic maintenance of a substantially uniform friction load produced by fluid pressure upon means driven by an electric prime mover includinga pass adapted to supply fiuid under pressure, a valve movable to control the pressure under which said fluid is supplied, elastic means straining to move the valve in one direction, a pressure chamber-,means constantly to maintain fluid pressuretherein, means associatedV with said pressure chamber' to cause the chamber pressure to tend to move the valve in the other direction, and an electric device movable proportionately to the-current consumed by the prime mover to vary proportionately the chamber' pressure whereby the valve opening is proportional to the current consumption.

13. An apparatus for the automatic maintenance of a substantially uniform friction load produced by fluidpressure upon Vmeans driven by an electric prime mover including a pass adapted to supply fluid under pressure, a valve movable to control the pressure under which said fluid is supplied, elastic means straining to move the valve in one direction, a pressure chamber, means constantly to maintain fluid pressure therein, Vmeans chamber to cause the chamber pressure to tend to move the valve in the other direction, and an electric device movable proportionately to the lcurrent consumed by the prime mover to vary proportionately the chamber pressure whereby the valve opening` is inversely proportional to the current consumption. f

14. An apparatus for theautomatic maintenance of a substantially uniform friction load produced by fluid pressure upon means driven by an electric prime mover including a pass adapted to supply fluid under pressure, a valve movable to control the associated with said pressurev pressure under which said fluid is supplied, elastic means straining to move the valve in one direct-ion, an electrically operable device actuable in response to changes in said friction load, fluid means co-operable with said device straining proportionally .to said friction load to move the valve in the opposite direction to provide a valve open- 'ing proportional to said friction load whereby said friction load is automatically maintained, and complementary means actuable byvfiuid flow through said pass to control the pressure therein.l Y

15. An apparatus for the automatic maintenance of a substantially uniform friction load produced by fiuid pressure upon means driven by an electric prime mover including a pass adapted to supply fluid under pressure, a valve movable to control the` pressure under which said fluid is supplied, lelastic means strainingto move thervalve in` one direction, a pressure chamber, means constantlyto maintain fluid pressure therein, means associated with said pressure chamber to cause the chamber Vpressure to Atend to move the valve in the other direction, an elastic device movable proportionately tothe current consumedby the prime mover to vary proportionately the chamber pressure whereby the valve opening is proportional to the current consumption, and complementary means actuable by fluid flow .through saidpass to control the pressure therein` Y 16. An apparatus for theautomatic main-` tenance of a substantially uniform loadproduced by fluid pressure upon means driven by an electric prime mover including a. valve to control said fluid pressure, means electrically operable by the current supplied the prime mover to maintain a valve opening inversely vproportional to the current consumed by the prime mover, and complementary means actuable by fluid flow, tending to prevent pressure changes.

In witness whereof, I have hereunto set myphand this 3rd day of March, 1925.

v ADOLPH F. MEYER. 

